Double doors are often used to close-off doorways and other openings that are too large for a single door. To securely lock double doors in their closed position, at least one of the doors must be anchored to the door frame. Various locking systems have been employed to securely lock double doors in their closed position. These systems typically include a bolt mounted to each door with each bolt being slidable into an anchoring hole formed in the door frame header or in the floor. With some of these systems, the bolts are mounted onto the face of each door. However, having the bolts exposed in this manner is often considered unsightly and not as secure as other systems. A more preferred type of bolt locking system includes a bolt and an actuating mechanism that are sunk into one or both doors along their respective free swinging side edge. This type of system locks the doors more securely because the bolt assembly is actually embedded in the door, making it inaccessible and stronger. In addition, with these so called flush bolt systems, when the doors are closed, the locking system is not visible and therefore do not detract from the natural beauty of the doors. Thus, such flush bolt locking systems are particularly popular with double French-type doors, which are chosen for their aesthetic features.
Such flush bolt systems are typically installed by using a hand chisel or router to cut a stepped recess into the side edge of each door of a sufficient depth to accommodate the bolt actuating mechanism of the locking system. The side recess is formed with a shallow step to accommodate a relatively thin (e.g., 1/8 inch thick) face plate used to cover the actuating mechanism. A deeper step is also cut to accommodate the actuating mechanism itself. A bore hole through which the bolt slides is drilled vertically down from the top edge of the door adjacent to its free swinging side edge and into the deeper stepped portion of the side recess. Another shallow recess is then formed around the top opening of the bolt hole to receive a relatively thin (e.g., 1/8 inch thick) guide plate having a hole for the locking bolt to pass through. In the past, such recesses have been formed by hand with a chisel or by using a router. In general, compared to using a router, hand chiseling is time consuming and more often results in recesses that are inconsistent in size from one door to the next. With flush bolt locking systems the dimensions of the recesses can be critical. However, when used to cut a stepped recess such as that for a flush bolt locking system, routers have still proven to be more time consuming and inconsistent than desirable.
Therefore, there is a need for a way to quickly form such stepped recesses, while consistently maintaining the accuracy of the recess dimensions from door to door.